A murder suspect who had been the subject of a vast police manhunt is believed to have lured two unarmed female constables to their deaths, police said, as tributes poured in for the officers who were fatally injured during a gun and grenade attack near Manchester.

Speaking from Greater Manchester police headquarters, where the flag was flying at half mast, Chief Constable Sir Peter Fahy said Fiona Bone, 32, and Nicola Hughes, 23, died after going out on routine patrol to check a reported burglary in Hattersley, Tameside, shortly before 11am.

Great Manchester Police Handout of Fiona Bone And Nicola Hughes who were killedi n the line of duty Photograph: PA

As they arrived at the property in Abbey Gardens, he said, they came under fire from bullets and a grenade. Cregan is believed, said Sir Peter, to either have made the 999 call himself or told someone else to make it.Police had no intelligence linking him to the address or the street, he said.

"It would appear Cregan has deliberately done this in an act of cold-blooded murder," Sir Peter told a press conference, adding that the 29-year-old's motive for the attack was, for the moment, "impossible to fathom".

Shortly after the incident Creganhanded himself in at a police station in Hyde. He was subsequently arrested on suspicion of the murder of both officers, as well as on suspicion of two counts of murder in relation to the killings of a father and son, who died in separate attacks this year.

Sir Peter said it appeared Cregan had been "protected by a criminal conspiracy to harbour him" and every effort would be made to bring those involved "to book".

Paying tribute to Bone and Hughes, he said they were "two very brave and courageous colleagues who exemplified the very best of British policing".

Bone, he said, was a "calm, gentle woman" and "excellent bobby" who had been in the midst of planning her wedding. Just this morning, she had spoken to her partner on the phone about invitations. She had been with the force for five years. Hughes, who had served three years in the force, was a "bubbly" karate fan who was a "good listener" and "couldn't do enough for people", he said.

Forensic officers search the scene outside a house in Hattersley, Tameside where two female police officers were shot Photograph: Christopher Furlong/Getty Images

David Cameron described their murders as "a shocking reminder of the debt we owe to those who put themselves in danger to keep us safe and secure".

In a statement released by Downing Street, Cameron said: "I want to offer my thoughts, along with those of the whole country, to the families, friends and colleagues at this difficult time."

The home secretary, Theresa May, said: "This is a deeply shocking incident and a terrible reminder of the risks that police officers face every day to keep our communities safe."

Greater Manchester police had been searching for Cregan, who has only one eye, for months even after David Short, 46, was killed at his home in Folkestone Road East, Clayton, Manchester, on 10 August. His 23-year-old son, Mark, an amateur boxer, was gunned down at the Cotton Tree pub in nearby Droylsden, on 25 May.

A £50,000 reward had been offered for information leading to Cregan's arrest.

Four men have already been charged in connection with Mark Short's murder and are due to enter pleas at Manchester crown court in November. Earlier this month, a 33-year-old man appeared at the same court charged with the murder of David Short.

Police at the cordon near Abbey Gardens in Hattersley, Tameside, Greater Manchester after the double shooting. Photograph: Bentley Moss/Cavendish Press

For the search to end in such a tragic way has cast a "dark shadow" over the force, said Assistant Chief Constable Garry Shewan.

"A long and dark shadow has been cast across Greater Manchester and my thoughts are with the officers' family, friends and colleagues. We will be doing everything we can to support them over the coming days and weeks."

The area around Abbey Gardens, where the incident took place, was cordoned off on Tuesday as a bomb disposal unit was reported to be seen nearby.

A 27-year-old woman, who did not want to be named, said her ex-boyfriend had witnessed the shootings. She told the Press Association he had seen someone outside a local house shoot the officers and then throw a grenade in the garden. "He said the officers hit the floor," she said. "Cregan then got into a silver BMW and drove off but he must have then gone on foot shortly after because my friend saw him on Stringer Avenue which is only down the road."

Greater Manchester shooting Photograph: BBC

Sir Hugh Orde, president of the Association of Chief Police Officers, said: "Whenever police officers and staff lose a colleague that loss is felt right across the police family. The thoughts of everyone in policing are with colleagues in Greater Manchester police, family and friends of the two officers at this time."

Derek Barnett, president of the Police Superintendents' Association of England and Wales, said: "Today once again we have seen how police officers pay the ultimate price in losing their lives to protect the public. Whilst we still don't know the full circumstances, this tragic situation demonstrates the uniqueness of the office of constable, a duty not to walk away from danger. It also serves as a reminder of the risks that officers face on a regular basis.

"At the beginning of their tour of duty these two officers would have had no idea what lay ahead of them. I'm sure few words will offer true comfort to the families, colleagues and friends at such a difficult time, but our thoughts and prayers are with them."

Police carry out a fingertip search at the cordon near Abbey Gardens in Hattersley. Photograph: Allan Bentley/ Cavendish Press

Bone and Hughes are the second and third to have died this year after a firearms incident.

PC Ian Dibell was killed by a single bullet wound to the chest after intervening in a dispute while off duty in Clacton-on-sea, Essex, in July. The suspected gunman, Peter Reeve, was found dead the next day with a gun.